Defines “large capacity ammunition feeding device” as a magazine, belt, drum, or feed strip that has an overall capacity of or can be converted to accept more than 10 rounds of ammunition (Sec. 403).

Exempts certain entities and individuals from the provisions of this bill, including, but not limited to the following (Sec. 403):

A department or agency of the United States;

A department, agency, or political subdivision of a state;

A qualified law enforcement officer employed by the United States or a state; and

An individual who retired in good standing with from law enforcement and is not otherwise prohibited from receiving a firearm.

Exempts certain categories of firearms from the provisions of this bill (Sec. 403):

semiautomatic assault weapons and magazines that were legally owned before the enactment of the bill;

firearms used for hunting and sporting activities.

Requires the Attorney General to instruct the Director of the National Institutes of Justice to conduct a study of incidents of mass shootings in the United States, examining issues including, but not limited to, the following (Sec. 406):

Childhood abuse and bullying;

Exposure to criminal acts;

Mental Illness;

The effectiveness and availability of mental health resources;

The availability of firearms; and

Depictions of violence in video games and entertainment.

Requires the director to submit to Congress the results of the study no later than 1 year after the study begins (Sec. 406).